1. Field of the Invention
The present invention relates to a siloxane polyimide and a heat-resistant adhesive containing the same, and more particularly to a solvent-soluble siloxane polyimide and a heat-resistant adhesive containing the same.
2. Description of Related Art
Heat-resistant adhesives containing an aromatic polyimide, etc. as a main component have been so far used in bonding between a base material and a copper foil of a flexible printed substrate. However, the aromatic polyimide is generally insoluble in ordinary organic solvents, and thus is used in the form of a solution of an aromatic polyamic acid as its precursor, which specifically requires an additional polyimidization reaction step with heating at a high temperature for a long time successively after application and drying of the solution. The polyimidization reaction step has such problems as occurrence of void phenomena and thermal deterioration of electronic parts per se.
JP-A-61-118424, JP-A-1-121325, etc. on the other hand, disclose solvent-soluble siloxane polyimides, but have such problems as low heat resistance, insufficient solubility in a variety of organic solvents, considerable curling of substrates when drying solution-applied flexible printed substrates, etc.